Check valves for microfluidic systems and methods thereof

Abstract

The present invention relates to microfluidic check valves, as well as fluidic cartridges including such check valves. In particular examples, the check valve includes a pre-stressed spring formed from a planar substrate. Various characteristics of the valves, such as size, profile, opening pressure, etc., can be tuned to provide desired performance when employed within a fluidic cartridge.

The invention claimed is: 
     
       1. A fluidic cartridge comprising:
 a first fluidic check valve comprising:
 a base comprising an inlet; 
 an elastomeric pad comprising a first surface and a second surface that opposes the first surface, wherein the first surface is configured to releasably contact the inlet; 
 a pre-stressed spring comprising a plurality of extended beams defined within a planar substrate and connected to a central support, wherein a surface portion of the substrate is configured to contact a surface portion of the base, and wherein the central support is defined within the substrate and configured to align with the second surface of the elastomeric pad, thereby providing a pressurized seal between the inlet of the base, the elastomeric pad, and the central support of the pre-stressed spring; and 
 a lid comprising a cavity, wherein the cavity is configured to encompass the pre-stressed spring and the elastomeric pad; 
 
 a first valve seat configured to accommodate the first check valve; and 
 a main microchannel in fluidic communication with the first valve seat. 
 
     
     
       2. The cartridge of  claim 1 , further comprising a diaphragm pump in fluidic communication with the first check valve. 
     
     
       3. The cartridge of  claim 2 , further comprising a second fluidic check valve in fluidic communication with the main microchannel. 
     
     
       4. The cartridge of  claim 1 , further comprising a chamber in fluidic communication with the first valve seat, wherein opening of the first check valve provides fluidic communication from the chamber to the main microchannel. 
     
     
       5. The cartridge of  claim 1 , further comprising one or more reaction channels in fluidic communication with the main microchannel and an air pocket having a dead-end that is in fluidic communication with the one or more reaction channels, thereby facilitating dead-end filling of the cartridge. 
     
     
       6. The cartridge of  claim 5 , further comprising a backflow channel in fluidic communication with the main microchannel and the air pocket. 
     
     
       7. A fluidic cartridge comprising:
 an input channel configured to deliver a sample; 
 a pumping chamber in fluidic communication with an on-chip diaphragm pump; a first fluidic check valve comprising:
 a first base comprising an inlet; 
 a first elastomeric pad comprising a first surface and a second surface that opposes the first surface, wherein the first surface is configured to releasably contact the inlet; 
 a first pre-stressed spring comprising a plurality of extended beams defined within a planar substrate and connected to a central support, wherein a surface portion of the substrate is configured to contact a surface portion of the first base, and wherein the central support is defined within the substrate and configured to align with the second surface of the first elastomeric pad, thereby providing a pressurized seal between the inlet of the first base, the first elastomeric pad, and the central support of the first pre-stressed spring; and 
 a first lid comprising a cavity, wherein the cavity is configured to encompass the first pre-stressed spring and the first elastomeric pad, wherein opening of the first check valve provides fluidic communication from the input channel to the pumping chamber; 
 
 a reaction channel; 
 a second fluidic check valve comprising:
 a second base comprising an inlet; 
 a second elastomeric pad comprising a first surface and a second surface that opposes the first surface, wherein the first surface is configured to releasably contact the inlet; 
 a second pre-stressed spring comprising a plurality of extended beams defined within a planar substrate and connected to a central support, wherein a surface portion of the substrate is configured to contact a surface portion of the second base, and wherein the central support is defined within the substrate and configured to align with the second surface of the second elastomeric pad, thereby providing a pressurized seal between the inlet of the second base, the second elastomeric pad, and the central support of the second pre-stressed spring; and 
 
 a second lid comprising a cavity, wherein the cavity is configured to encompass the second pre-stressed spring and the second elastomeric pad, wherein opening of the second check valve provides fluidic communication from the pumping chamber to the reaction channel. 
 
     
     
       8. The cartridge of  claim 1 , wherein the base further comprises an outlet configured to be in fluidic communication with the inlet upon displacement of the elastomeric pad away from the inlet. 
     
     
       9. The cartridge of  claim 1 , further comprising:
 a channel layer disposed between the planar substrate and the lid, wherein the channel layer comprises a chamber configured to accommodate a dimension the pre-stressed spring and a channel output configured to be in fluidic communication with the inlet upon displacement of the elastomeric pad away from the inlet. 
 
     
     
       10. The cartridge of  claim 1 , wherein the elastomeric pad and the pre-stressed spring comprises a single structure. 
     
     
       11. The cartridge of  claim 1 , wherein the base further comprises a ridge surrounding the inlet. 
     
     
       12. The cartridge of  claim 11 , wherein the elastomeric pad further comprises an indent configured to accommodate the ridge, thereby providing a seal between the ridge and the indent. 
     
     
       13. The cartridge of  claim 1 , wherein the base further comprises a recess configured to accommodate the planar substrate of the pre-stressed spring. 
     
     
       14. The cartridge of  claim 1 , wherein the lid is further configured to contact a surface portion of the base. 
     
     
       15. The cartridge of  claim 1 , wherein the cavity is configured to provide a conformal surface in proximity to a surface profile of the pre-stressed spring. 
     
     
       16. The cartridge of  claim 1 , in which the first fluidic check valve is a microfluidic check valve and/or a normally closed check valve. 
     
     
       17. The cartridge of  claim 1 , further comprising an adhesive layer disposed between the base and the planar substrate and/or between the planar substrate and the lid. 
     
     
       18. The cartridge of  claim 1 , wherein a first material for the planar substrate is different than a second material for the elastomeric pad. 
     
     
       19. The cartridge of  claim 1 , wherein the planar substrate comprises a laser-cut thermoplastic; and/or wherein the elastomeric pad comprises silicone. 
     
     
       20. The cartridge of  claim 11 , wherein the ridge is a concentric annular boss and wherein the elastomeric pad rests against the concentric annular boss over the inlet.